The present invention relates to photographic copying machines in general, and more particularly to improvements in photographic copying machines of the type wherein the platform which supports an original during copying is not shielded from surrounding light and the copying is regulated by automatic exposure controls. Still more particularly, the invention relates to photographic copying machines wherein the color- and/or density-monitoring detector means of the exposure controls are located outside of the path of copying light and face the illuminated original.
Copying machines of the above outlined character are used primarily for the making of reproductions of discrete originals or for the reproduction of images of differently dimensioned and/or configurated originals. As a rule, the originals are placed onto and removed from the platform by an attendant. This renders it necessary to install the platform in such a way that it is readily accessible for positioning and removal of originals. In order to allow for accurate evaluation of color composition and/or density of an original, certain presently known copying machines embody an opaque glass plate which shields a freshly inserted original and the detector means from surrounding light (including daylight and/or light furnished by one or more room-illuminating light sources) to thus insure accurate measurements of color distribution and/or density of the original preparatory to the making of one or more reproductions. It is also known to employ a bellows which extends between the platform and the detector means when the original is ready for copying. Such bellows serve the same purpose as the aforementioned opaque plates, i.e., they shield the detectors from surrounding light during evaluation of the freshly inserted original so that the signal or signals transmitted by the detector means are sufficiently accurate to insure the making of satisfactory reproductions.
The opening or closing of bellows and the movement of a plate-like or otherwise configurated shielding device to and from operative position takes up a substantial amount of time. Moreover, the presence of such shielding means invariably reduces, at least to a certain extent, the accessibility of the platform.